This invention relates to a copolymer having peroxy bonds in the molecule thereof. More particularly the present invention relates to a novel copolymer having peroxy bonds in the molecule thereof, a use thereof and a process for producing the same. A copolymer having peroxy bonds in the molecule thereof is very useful as a polymerization initiator, because monomers having double bonds therein other than those which are used to produce said copolymer are subjected to a polymerization using the same as a polymerization initiator, whereby a blocked copolymer can be obtained easily.
A method for producing a copolymer having peroxy bonds in the molecule thereof which comprises polymerizing monomers having double bonds therein with diacyl type polymeric peroxides not having ester bonds therein has heretofore been known.
There are several reports concerning this method.
For example, Sugimura et al. reported in Journal of the Chemical Society of Japan, Industrial Chemistry Section 69 718 (1966) and A. E. Woodward et al. reported in J. Polymer Sci. 14 126 (1954) and ibid. 17 51 (1955) that styrenes were polymerized using a polyphthaloyl peroxide, thereby obtaining polystyrenes having peroxy bonds in the molecule thereof.
Further, N.S. Tsvetkov et al. reported in Chem. abst. 62 5,337.sup.c (1965), ibid. 62 13,238.sup.f (1965), ibid. 70, 29,399.sup.t (1969) and Eur. Polym. J. (suppl.) 1969, 489-493 etc. that styrene or methyl methacrylate was subjected to a polymerization using a diacyl type polymeric peroxide ##STR1## (wherein n is 2-10 and x is 16-35) having polymethylene bonds therein, thereby obtaining a polystyrene or polymethyl methacrylate having peroxy bonds in the molecule thereof.
However, the conventional polymers having peroxy bonds in the molecule thereof, such as those described in the foregoing have disadvantages in that
(1) As the solubility of the polyphthaloyl peroxide or the diacyl type polymeric peroxide having polymethylene bonds therein, which have no ester bonds therein, such as those described hereinbefore, in a monomer having double bonds therein or an organic solvent is very small, they can be charged into the monomers only in a ratio of 0.5-1 part by weight based on 100 parts by weight of the monomer, in the polymerization procedure,
(2) and that owing to the disadvantage (1) described in the foregoing, it is required for obtaining the polymers with good yield, to lengthen the polymerization time, or to increase the polymerization temperature, with the result being that the peroxy bonds which were introduced into the molecule of the polymer are cleaved by the heat.
Accordingly, the obtained polymer has a very small number of peroxy bonds per unit average molecular weight, e.g. in case the polymer is a polystyrene having peroxy bonds in the molecule thereof, the number of the peroxy bonds is at most 1-2 per 100,000 of the average molecular weight.
Further, the copolymer having peroxy bonds in the molecule thereof is reported to be a kind of a block copolymer which comprises a polymer block which was formed by polymerization of monomers having double bonds therein and a peroxide block.
Also, in this case, since, owing to the disadvantage (1) the conventional diacyl type polymeric peroxide and the polyphaloyl peroxide can be charged into the monomer only in a small and narrow range of ratio of the same to the monomer, the average molecular weight of the obtained block copolymer having peroxide bonds in the molecule thereof was necessarily limited narrowly.
Accordingly, when the conventional copolymers having peroxy bonds in the molecule thereof are used as a polymerization initiator in producing a block copolymer by polymerizing monomers having double bonds therein, other than those which were used to produce said polymerization initiator, they were so weak in activity as a polymerization initiator that almost no industrial value was recognized for them.